Field
Aspects of the present disclosure relate to semiconductor devices, and more particularly to a high density, area efficient thin-oxide decoupling capacitor using a conductive gate resistor.
Background
Capacitors are passive elements used in integrated circuits for storing an electrical charge. Capacitors are often made using plates or structures that are conductive with an insulating material between the plates. The amount of storage, or capacitance, for a given capacitor is contingent upon the materials used to make the plates and the insulator, the area of the plates, and the spacing between the plates. The insulating material is often a dielectric material. Metal-insulator-metal (MIM) capacitors are one example of a parallel plate capacitor, in which the insulator is the dielectric, and the plates are made of a metal material.
Parallel plate capacitors are frequently employed in semiconductor dies to provide capacitance to circuitry on the semiconductor die. Parallel plate capacitors are increasingly used to improve performance of devices that operate at increasingly higher frequencies. For example, parallel plate capacitors may be added to semiconductor dies having radio frequency (RF) circuitry to provide bypass capacitance. This usage of a capacitor may be referred to as a decoupling capacitor. A decoupling capacitor is a capacitor that decouples one portion of a circuit (e.g., an electrical network) from another portion of the circuit. In this arrangement, noise generated by other portions of the circuit is shunted through the capacitor, which reduces the effect of the noise on the remaining portions of the circuit. That is, a decoupling capacitor may be used to bypass a power supply or other high impedance component of the circuit.
The fabrication of decoupling capacitors, however, usually increases the cost of producing a semiconductor die by, for example, increasing the number of processing steps and increasing the number of masks to produce a die. In addition, gate leakage of decoupling capacitors (e.g., due to oxide thickness) becomes a significant problem at advanced process nodes.